Our goal is to understand the basis of directed cell motility in the embryo and in tissue culture. In this grant we will explore specifically the role of galvanotaxis in embryonic morphogenesis and examine the molecular basis for the galvanotactic response. Internal electric fields will be identified and mapped in two regions where morphogenesis is occurring: 1) around the neural tube at the time of neural crest migration and 2) around epidermal wounds in Xenopus tail as wound healing commences. If electric fields are found in the appropriate orientation, we will perturb them with drugs or with injected current to see if this alters morphogenetic behavior. The basis for the galvanotactic response will be studied in tissue culture with an emphasis on the effects of electric fields on membrane permeability, on the cytoskeleton, and on the distribution of proteins in the plasma membrane. Localized membrane permeability changes will be detected with the extracellular vibrating probe technique as well as the Ca2+- sensitive fluorescence of fura-2. Electric field effects on the cytoskeleton will be studied by injecting fluorescent analogues of actin, alpha-actinin and vinculin into living fibroblasts and studying the redistribution of these proteins upon field application. These studies will not only allow us to examine factors responsible for mediating the galvanotactic response, but also will allow us to explore the more fundamental processes underlying cell motility itself. We will also examine the redistribution of plasma membrane proteins that might be responsible for mediating the galvanotactic response using the relatively non-specific technique of lectin binding and more specific monoclonal antibodies directed against cell surface proteins. The antibodies will be screened to identify those against proteins that do redistribute in the electric field. Such antibodies will then b used to block galvanotaxis in an effort to find a cell surface molecule that mediates this response.